In various sources that deal with the history of Indian state Kerala, it is stated that they had trade contacts with ancient Egypt, as well as with ancient Greece and ancient Rome, these contacts were through maritime routes. They were direct routes as well as through arab traders. Here is one source about Keralan historyhttp://www.prokerala.com/kerala/history/history.htm#h2Among buddhist writers there are some who think that Rome had also intellectual contact with India, like Alex Wayman for example.

The kingdom of Gandhara had a lot of contact with the Greco-Roman world. And, you can see that influence in the famous Buddhist statues from that time. I also recall that there was a Buddhist community living in Alexandria.

I have heard that Roman coins were found in Vietnam some years ago.the silk and other trading routes are very ancient.

in any matters of importance. dont rely on me. i may not know what i am talking about. take what i say as mere speculation. i am not ordained. nor do i have a formal training. i do believe though that if i am wrong on any point. there are those on this site who i hope will quickly point out my mistakes.

Yes, silk was taken from China through the seas to India and from there further to Rome. Use of silk was widespread, traces of silk have been found from all parts of Roman empire, even from outpost places like Britain. They imported from the East also many other things like grains of rice, which was so expensive that it could only be used as a medicine. And it may be the product that came from Vietnam (?).